Process of tanning with esters of chloracetic acid



r 2,746,838 e ,atented ll 'lay 22, 1956 PROCESS OF TANNING WITH ESTERS OF CHLORACETIC ACID No Drawing. Application July 28, 1952, Serial No. 301,386

7 Claims. (Cl. 894.33)

This invention relates to a new tanning process for skins and hides.

It was found that chloracetic acid esters of hydroxyl compounds, containing alkyl groups of 8-25 carbon atoms, may be used for tanning purposes.

It was further found that chloracetic acid esters of the so-called fatty alcohols are particularly suitable for tanning skins and hides.

The new tanning agents have a high aflinity for the animal collagen fibre and can be worked smoothly into the skins and/ or hides. For reasons of expediency, the treatment should be done in the presence of acid-binding agents, as, for example, caustic alkaline, alkali carbonates, such as soda ash, ammonia, ammonium carbonate, organic nitrogen bases, such as pyridium and the like. The leathers thus treated are of good quality and exhibit chemical resistance against aqueous ammonia or alkali solutions.

The tanning process in accordance with the invention may also be applied in conjunction with common mineral-, vegetable-, or synthetic tanning agents, the known tanning process being applied either before or after the process of the invention. The properties of the tanning agents used in accordance with the invention depend to a certain extent on the character of the ester residues, so that the tanning agents adopt the character of fatty tanning agents with increasing length of the chain of the alkyl radical.

The new tanning agents are suitable for the tanning of animal skins and hides of any kind which will be prepared in the conventional manner in the water-workshop by soaking, slackening and/or liming, deliming, macerating, and, if necessary, pickling.

The chloracetic acid esters to be used in the tanning process can be produced in a known manner, as for example, by esterification or re-esterification of chloracetic acid or its functional derivatives, such as halides or esters, with hydroxyl compounds containing alkyl groups of 8-25 carbon atoms. Such hydroxyl compounds are preferably alcohols containing aliphatic residues of higher molecular weight, i. e., with 8-20 carbon atoms. Such aliphatic alcohols (of at least 8 carbon atoms in the molecule), as, for example, octyl alcohol, dodecyl alcohol, octadecyl alcohol, oleyl alcohol, and the homologues or mixtures of the same, may be obtained by reduction of natural fats and oils or by oxidation of parafiins or by the so-called Oxo process, i. e., the reaction of CO and Hz with olefins in the presence of a cobalt catalyst. Further suitable hydroxyl compounds for building up the esters are alkylcyclohexyl alcohols with alkyl residues of approximately C3-C18 carbon atoms, naphthenyl alcohols, aromatic oxy compounds, alkylated in the nucleus, as, for example, alkyl phenols with alkyl residues of about 8-20 carbon atoms.

Examples for the tanning agents used in accordance with the invention are chloracetic acid dodecyl ester, chloracetic acid octadecyl ester, the chloracetic acid es- 2 ters of a mixture of fatty alcohols with 10-14 carbon atoms, the chloracetic acid esters of a mixture of unsaturated aliphatic alcohols with 14-1-6 carbon atoms, furthermore the chloracetic acid esters of a mixture of alkyl phenols with '10-16 carboii'atoms in the alkyl chain.

The process of the invention can be elfected by intimately contacting the skins or hides to be tanned with the chloracetic acid esters which are preferably employed as concentrated as possible, either as such or in solution and emulsion, respectively, in an amount of about 2-20%, based on the weight of the material to be treated. After fulling, the leather is worked upon and finished in the conventional manner.

The following examples, in which is based on the weight of the skin, further illustrate the invention without limiting the same.

Example 1 Depickled rabbit skins are preliminarily treated for one hour with 0.3% hydrochloric acid, 6% common salt, and water. Then tanning is effected for one hour with 70% water, 3% common salt, and 0.5% chromium oxide in the form of weakly alkaline chromium sulfate. The leather is left wet for one week and then properly squeezed.

Thereupon, tanning is effected with 16% chloracetic acid dodecyl ester and 3.5% sodium carbonate. After 15 minutes hot air at a temperature of F. is blown in. Then the leather is left for 20 days. The reaction of the leather is now practically neutral. Upon this, the leather is washed for two hours with 0.5 sodium carbonate and 200% water at 86 F.; thereafter, it is properly rinsed. Finally, the leather is staked. The leather shows a good firmness; it is soft and smooth.

Instead of chloracetic acid dodecyl ester, the same quantity of chloracetic acid-p-dodecyl-phenyl ester may also be applied.

Example 2 Depickled rabbit skins are preliminarily tanned at a temperature of 86 F. with 1.5% of a 30% aqueous formaldehyde solution and 0.7% sodium bicarbonate in 200% water, the formaldehyde and sodium bicarbonate solutions being added in three portions at intervals of 30 minutes. After 3 hours of tanning, the leather is taken out and left wet. Thereafter, final tanning is done with chloracetic acid oleyl ester in the same manner as described in Example 1. The leather is thereby well tanned and obtains a smooth quality.

Instead of chloracetic acid oleylester, the chloracetic acid ester of a mixture of alcohols obtained in well known manner by addition of CO and Hz to olefins of the chain length of C12-Cie, in the presence of a cobalt catalyst and reduction of the resulting aldehydes, may also be used.

Example 3 Depickled cleaved neat skins are tanned for two hours with 5% of a chloracetic acid ester mixture of unsaturated fatty alcohols C14-C1s and 50% water. The ester mixture is applied in the form of an aqueous emulsion, with the sodium salt of an alkyl sulfate mixture C1-C9 serving as emulsifier. The treated skins are stored for a longer time, then they are washed and dried. The pieces which did not show a sufficient tanning effect before storing are now well tanned, and have a good leather character. After a longer time of storage, the leather is fulled up, rinsed for one hour with 1% sodium bicarbonate and 200% water at a temperature of 95 F. Thereafter it is dyed, liquored, and finished in the conventional manner.

What is claimed is:

1. Process for tanning skins and hides which comprises contacting skins and hides with an ester of chloracetic acid and a hydroxyl compound containing an alkyl group of 8-25 carbon atoms and recovering the tanned material.

2. Process according to claim 1, in which said hydroxyl compound is a fatty alcohol. I

3. Process accordingto claim 1, in which said hydroxyl compound is an unsaturated alcohol.

4. Process according to claim 1, in which said bydroxyl compound is dodecyl alcohol.

5.Proccss according to claim 1, in which said by droxyl compound is tetradccyl alcohol.

UNITED STATES PATENTS References Cited in the file of this patent 2,131,146 Schlack Sept. 27, 1938 2,183,754 Schlack Dec. 19, 1939 2,523,324 Putnam Sept. 26, 1950 Putnam Sept. 26, 1950 

1. PROCESS FOR TANNING SKINS AND HIDES WHICH COMPRISES CONTACTING SKINS AND HIDES WITH AN ESTER OF CHLORACETIC ACID AND A HYDROXYL COMPOUND CONTAINING AN ALKYL GROUP OF 8-25 CABON ATOMS AND RECOVERING THE TANNED MATERIAL. 